PLATE XL. 



Townsendia exscapa. 



Fig. 4. Cutinized epidermis of stem, cross section. R, outer tangential 

 wall; S, inner tangential wall. X 650. 

 Cork cells, cross section, x 650. 

 Collenchyma cells, cross section, x 650. 

 Collenchyma cells, longitudinal section, x 650. 

 Short sclerenchyma cells, cross section, x 650. 

 Short sclerenchyma cells, longitudinal section. X 650. 

 Coi-tex cells, cross section, x 650. 

 Cortex cells, longitudinal section, x 650. 

 Pith cells, cross section, x 650. 

 Pith cells, longitudinal section. X 650. 



Small portion of xylem, cross section, showing: a, tracheids; 

 b, wood parenchyma cells, x 650. 

 Fig. 15. Tracheids, as seen in a longitudinal section, when isolated from 

 the wood parenchyma cells by means of chromic acid. X 650. 



